Phylogeny and Systematics of Lemnaceae, the Duckweed Family
Systematic Botany (2002), 27(2): pp. 221±240 q Copyright 2002 by the American Society of Plant Taxonomists Phylogeny and Systematics of Lemnaceae, the Duckweed Family DONALD H. LES,1 DANIEL J. CRAWFORD,2,3 ELIAS LANDOLT,4 JOHN D. GABEL,1 and REBECCA T. K IMBALL2 1Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut 06269-3043; 2Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, Ohio 43210; 3Present address: Department of Ecology and Evolutionary Biology, The University of Kansas, Lawrence, Kansas 66045-2106; 4Geobotanisches Institut ETH, ZuÈ richbergstrasse 38, CH-8044, ZuÈ rich, Switzerland Communicating Editor: Jeff H. Rettig ABSTRACT. The minute, reduced plants of family Lemnaceae have presented a formidable challenge to systematic inves- tigations. The simpli®ed morphology of duckweeds has made it particularly dif®cult to reconcile their interspeci®c relation- ships. A comprehensive phylogenetic analysis of all currently recognized species of Lemnaceae has been carried out using more than 4,700 characters that include data from morphology and anatomy, ¯avonoids, allozymes, and DNA sequences from chloroplast genes (rbcL, matK) and introns (trnK, rpl16). All data are reasonably congruent (I(MF) , 6%) and contributed to strong nodal support in combined analyses. Our combined data yield a single, well-resolved, maximum parsimony tree with 30/36 nodes (83%) supported by bootstrap values that exceed 90%. Subfamily Wolf®oideae is a monophyletic clade with 100% bootstrap support; however, subfamily Lemnoideae represents a paraphyletic grade comprising Landoltia, Lemna,and Spirodela. Combined data analysis con®rms the monophyly of Landoltia, Lemna, Spirodela, Wolf®a,andWolf®ella.
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